The invention generally relates to inflatable cushions such as air bags and other inflatable products. The present invention is also related to a method of creating a reinforced joint or seal connecting two pieces of laminated or coated material used to form the cushion.
The present invention is useful with various products comprising two joined, sealed, bonded or laminated fabrics where the seam or seal is subject to high and/or sudden pressure loads.
Numerous products, such as inflatable air bags, cushions and mattresses, are made of bonded, coated or laminated material. Adjacent pieces of material are attached at a joint, seam or seal by welding, gluing or otherwise bonding the material together.
The primary embodiment of the invention is as an inflatable air bag using laminated or coated fabrics having low or zero permeability to enable the bag to retain its pressure for a relatively long period of time. This type of bag is useful in providing occupant protection during a vehicle rollover or multiple impact accident or an event that requires the cushion to be inflated for a long duration. To retain the bag pressure, the various panels of material forming the bag are coated with a polyurethane or other bondable coating. These panels are then joined together. As is known in the art, the panels can be sewn together, however, the resulting needle holes will create leak paths for the inflation gas. Alternatively, the panels can be glued or welded together such as by using sonic, RF (radio frequency) or other heat welding techniques. This type of construction (gluing or welding) eliminates the needle holes of the sewn construction, however, the resulting welded or glued joints can be pulled apart relatively easily. The present invention provides a method and apparatus for reinforcing these bonded (glued or welded) joints. The efficiency of manufacture is also an important aspect of any product. As will be apparent from the description below, an air bag (generically a cushion) can be assembled on a flat work surface with a minimal amount of manipulation of the various parts of the air bag.
It is an object of the present invention to provide a cushion with an improved joint for strength and ease of manufacturing.
Accordingly the invention comprises: an inflatable cushion comprising: a first panel and a second panel attached together generally along a peripheral joint to form the inflatable cushion. The joint is subjected to a peeling load upon inflation of the cushion which tends to separate the joint. Each of the first and second panels includes a first layer comprised of a flexible, structural material and a second, bondable layer. The bondable layer is formed of material that is joinable to an adjacent, facing bondable layer to form the joint. Reinforcement means are provided for preventing the joint from separating. The reinforcement means includes a first strip of material having a structural layer and a bondable layer, and a second strip of material having a structural layer and a bondable layer. The first and second strips are overlaid and sewn together at a seam to retard separation of the strips. The seam separates each of the strips into two portions, wherein the structural layers face each other and the bondable layers face outwardly facing a corresponding bondable layer of the first and second panel. The bondable layers of the first and second strips are joined on one side or both sides of the seam to a corresponding bondable layer of one or the other panel.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.